Hydrocyclone plant

ABSTRACT

A hydrocyclone plant comprises a multiplicity of hydrocyclones arranged in groups of at least two hydrocyclones, each group being made in a single piece. The hydrocyclones extend substantially radially in an annular space for a liquid mixture to be separated. The inlet space extends concentrically around a cylindrical heavy fraction space for receiving a heavy fraction of the liquid mixture from the hydrocyclones. According to the invention, the hydrocyclone groups are distributed around the cylindrical heavy fraction space in the circumferential direction and are spaced from one another in the inlet space to allow the liquid mixture to flow between adjacent hydrocyclone groups.

FIELD OF THE INVENTION

The present invention relates to a hydrocyclone plant, comprising amultiplicity of hydrocyclones arranged in groups of at least twohydrocyclones, each hydrocyclone having an elongated separation chamberwith two opposite ends, at least one inlet for a liquid mixture to beseparated, a light fraction outlet at one end of the separation chamberfor a created light fraction and a heavy fraction outlet at the otherend of the separation chamber for a created heavy fraction. There arewalls defining a cylindrical heavy fraction space, which communicateswith the heavy fraction outlets, an annular inlet space, which extendsconcentrically around the heavy fraction space and communicates with theinlets of the hydrocyclones, and an annular light fraction space, whichextends concentrically around the inlet space and communicates with thelight fraction outlets. Each hydrocyclone extends substantially radiallyin said annular inlet space, and each group of hydrocyclones is made inone single piece.

BACKGROUND OF THE INVENTION

A hydrocyclone plant of the general kind described is known from U.S.Pat. No. 4,190,523, in which each hydrocyclone group forms a disc havinga number of radially oriented hydrocyclones, said disc-shapedhydrocyclone groups being stacked. This known plant is not practical touse for applications which require relatively long hydrocyclones, sincethe discs would be too large and heavy. For instance, when cleaningfiber pulp suspensions by means of this plant, the required longhydrocyclones would result in discs having a diameter exceeding twometres. Such large discs would be difficult to disassemble from thestack of discs for servicing and repairing individual hydrocyclones. Theobject of the present invention is to provide a hydrocyclone plant ofthis kind, which is compact, is suited for relatively longhydrocyclones, and enables easy servicing of the individualhydrocyclones.

SUMMARY OF THE INVENTION

In accordance with the invention, the foregoing object is obtained bymeans of a hydrocyclone plant of the kind initially stated, which mainlyis characterized in that the groups of hydrocyclones are distributedaround the cylindrical heavy fraction space in the circumferentialdirection and are spaced from one another in the inlet space to allowthe liquid mixture to flow between adjacent groups of hydrocyclones.

Each group of hydrocyclones preferably comprises three hydrocyclones,and is releasably attached to said walls.

Each hydrocyclone is suitably designed with a cylindrical chamber, whichcommunicates directly with the inlet and the light fraction outlet, anda tapered chamber, which communicates directly with the heavy fractionoutlet, the cylindrical chambers in each group of hydrocyclonesextending in parallel with one another, whereas the centre axes of thetapered chambers of the group converge in direction towards the apexesof the tapered chambers. In this manner the hydrocyclones of each groupof hydrocyclones can be packed closer to one another.

In each hydrocyclone the central axis of the cylindrical chamber and thecentral axis of the tapered chamber suitably form an angle to oneanother, such that in an axial section through the hydrocyclone the wallof the chambers coincide with a straight line.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described more closely with reference to theaccompanying drawings in which:

FIG. 1 schematically shows a section of a hydrocyclone plant accordingto the invention;

FIG. 2 is a section along the line II--II in FIG. 1;

FIG. 3 is a section along the line III--III in FIG. 1; and

FIG. 4 is a section along the line IV--IV in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The hydrocyclone plant shown in the figures comprises a number ofelongated hydrocyclones 1 arranged in groups of three hydrocyclones.Each hydrocyclone 1 has a separation chamber consisting of a cylindricalchamber 2 and a conical chamber 5. The cylindrical chamber 2 has aperipheral inlet 3 for a liquid mixture to be separated and a centrallight fraction outlet 4 for a created light fraction. The conicalchamber 5 has a heavy fraction outlet 6 at the apex of the conicalchamber 5 for a created heavy fraction. Three cylindrical verticalwalls, an inner wall 7, an outer wall 8 and an intermediate wall 9 arearranged concentrically with one another and define a cylindrical heavyfraction space 10 in the interior of the inner wall 7, an annular inletspace 11 between the inner wall 7 and the intermediate wall and anannular light fraction space 12 between the intermediate wall 9 and theouter wall 8. The walls 7-9 are provided with bottom walls 13-15, whichhave an outlet member 16 for heavy fraction, and outlet member 17 forlight fraction and an inlet member 18 for the liquid mixture to beseparated.

The groups of hydrocyclones 1 extend substantially radially in theannular inlet space 11 and are evenly distributed around the cylindricalheavy fraction space 10 on several levels along the cylindrical walls7-9.

The inlet 3, the heavy fraction outlet 6 and the light fraction outlet 4of the hydrocyclones communicate with the inlet space 11, the heavyfraction space 10 and the light fraction space-12, respectively. Eachgroup of hydrocyclones is made in one single piece (FIG. 3 and 4), whichis releasable from the hydrocyclone plant via a hole arranged in theouter wall 8 in front of said piece. Said hole is normally closed by alid 19.

In each group of hydrocyclones 1 the cylindrical chambers 2 extend inparallel with one another, whereas the centre axes of the conicalchambers 5 converge in direction towards the apexes of the conicalchambers 5. In each hydrocyclone 1 the centre axis of the cylindricalchamber 2 and the centre axis of the conical chamber 5 form an angle αto one another, such that in an axial section through the hydrocyclone 1the wall of the chambers 2,5 coincide with a straight line 20 (FIG. 4).

During operation the liquid mixture to be separated is pumped to theinlet space 11 via the inlet member 18. In the inlet space 11 the liquidmixture flows under a relatively little flow resistance between thegroups of hydrocyclones to the individual hydrocyclones 1 and entersthese via the inlets 3. In the hydrocyclones 1 the liquid mixture isseparated into a light fraction and a heavy fraction, which flowsthrough the heavy fraction outlet 6 and which is collected in the heavyfraction space 10, from which the heavy fraction is discharged from thehydrocyclone plant via the outlet member 16. The light fraction flowsthrough the light fraction outlet 4 and is collected in the lightfraction space 12, from which the light fraction is discharged from thehydrocyclone plant via the outlet member 17.

We claim:
 1. A hydrocyclone plant for separating a liquid mixture into aheavy fraction and a light fraction, said plant comprising:amultiplicity of elongated hydrocyclones arranged in groups of at leasttwo hydrocyclones, each group of hydrocyclones being made in a singlepiece, each hydrocyclone having an elongated separation chamber with twoopposite ends, at least one inlet for a liquid mixture to be separated,a light fraction outlet at one end of the separation chamber for a lightfraction and a heavy fraction outlet at the other end of the separationchamber for a heavy fraction, and walls defining a cylindrical heavyfraction space communication with the heavy fraction outlets, an annularinlet space extending concentrically around said heavy fraction spaceand communicating directly with the inlets of the hydrocyclones, and anannular light fraction space extending concentrically around saidannular inlet space and communicating with the light fraction outlets,each hydrocyclone extending substantially radially in said annular inletspace, said groups of hydrocyclones being distributed around thecircumference of the cylindrical heavy fraction space and being spacedfrom one another in said annular inlet space to allow said liquidmixture to flow between adjacent groups of hydrocyclones.
 2. Ahydrocyclone plant according to claim 1, wherein each group ofhydrocyclones comprises three hydrocyclones and is releasably attachedto said walls.
 3. A hydrocyclone plant according to claim 1, whereineach separation chamber comprises a cylindrical chamber communicatingdirectly with the inlet for the liquid mixture and the light fractionoutlet, and a tapered chamber communicating directly with the heavyfraction outlet the cylindrical chambers of each group of hydrocyclonesextend in parallel with one another, and the central axes of the taperedchambers converge towards the pieces of the tapered chambers.
 4. Ahydrocyclone plant according to claim 3, wherein the central axes of thecylindrical and tapered chambers of each hydrocyclone form an angle withone another, such that in an axial section through the hydrocyclone thewall of the chambers coincide with a straight line.